const fp = require('lodash/fp');
const lodash = require('lodash');

const cars = [
    {name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true},
    {name: 'Spyker C12 Zagatoo', horsepower: 650, dollar_value: 648000, in_stock: false},
    {name: 'Japuar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false},
    {name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false},
    {name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true},
    {name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: false}
];

// 练习1
let isLastInStock = fp.flowRight(car => fp.prop('in_stock', car), fp.last);
console.log(isLastInStock(cars));

// 练习2
let getFirstCarName = fp.flowRight(car => fp.prop('name', car), fp.first);
console.log(getFirstCarName(cars));

// 练习3
let _average = function (xs) {
    return fp.reduce(fp.add, 0, xs) / xs.length;
}

let getDollarValues = lodash.curry(fp.map)(car => car.dollar_value);
let averageDollarValue = fp.flowRight(_average, getDollarValues);
console.log(averageDollarValue(cars));

// 练习4
let _underscore = fp.replace(/\W+/g, '_');
let transformName = fp.flowRight(_underscore, fp.toLower, car => fp.prop('name', car));
let sanitizeNames = cars => fp.map(transformName, cars);
console.log(sanitizeNames(cars));